udp

问题 when the send(or write) buffer is going to be full, let me say, only theres is only 500 bytes space. if I have a NONBLOCKING fd, and do n = send(fd, buf, 1000,0) here I wll get n<0, and I can get EWOULDBLOCK or EAGAIN error. my questions are: 1 here, the send write 500 bytes into the send buffer or 0 bytes to the send buffer? 2 if 500 bytes are sent to the buffer and if the fd is a UDP socket, then the datagram is split into 2 parts? 3 I need to use the fd to send many datagrams, if this time

问题 Can I perform a UDP broadcast packets on my machine? I don't have a network, i just have my cheap linux box. I want to have a server broadcasting a packet and two or more clients in the same machine receiving them. Is that possible? What IP do I use? @gravyface gave me hope but I tried: 1) server sending to 127.255.255.255:54321 and clients listenting to 0.0.0.0:54321. 2) server sending to 127.255.255.255:54321 and clients listening to 127.0.0.1:54321. 3) server sending to 127.255.255.255

问题 Can I perform a UDP broadcast packets on my machine? I don't have a network, i just have my cheap linux box. I want to have a server broadcasting a packet and two or more clients in the same machine receiving them. Is that possible? What IP do I use? @gravyface gave me hope but I tried: 1) server sending to 127.255.255.255:54321 and clients listenting to 0.0.0.0:54321. 2) server sending to 127.255.255.255:54321 and clients listening to 127.0.0.1:54321. 3) server sending to 127.255.255.255

问题 If i open a raw socket, and send udp packets with a wrong checksum, would the packets be dropped other side by the tcp/ip stack? 回答1: Yes they would be dropped. If you need more reliable communication you're much better off using TCP. for more information, take a look at this: http://www.diffen.com/difference/TCP_vs_UDP UDP there's no guarantee that the packets will even be sent, let alone received. If they are in fact received though, they are checked. If they fail checksum they are dropped.

问题 I have two scripts, first sends a broadcast, second is receiving UDP packets. It is working only when the receiving script has his IP address set (via bind) to 0.0.0.0 . Why? This address should be something like "not existing address", so how can the script have it set like his own address? Why 127.0.0.1 (or exactly 192.168.0.xx ) does not work? Thank you, RA 回答1: Probably your machine has two or more interfaces with different IPs, as you already know the 127.0.0.1 IP means your local

问题 On a POSIX system, if sock_fd is an UDP socket, will write(sock_fd, data, size) always return size or -1? I.e., if write() does not fail, will the requested chunk of data always be written in its entirety, implying that, if the return value is not -1, then I can always ignore the actual return value? It seems to me that this should be the case, but no man page seems to state it clearly. EDIT: I suppose there are two possible answers. Either it is stated somewhere, but I haven't found it, or

问题 I have a client/server topology in NS3 and I want to calculate the throughput of UDP traffic on the server. This line of code sink = StaticCast<PacketSink> (tcpServerApp.Get (0)); does not work because it can only be used in calculating the throughput of TCP packets. How can I calculate throughput for the received UDP traffic on the server? Thanks 回答1: You can calculate the throughput of UDP packets using the following code. You should use this code after Simulation::Run(); uint64_t rxBytes =

问题 I have a loop running in the main() function of my program that looks as follows while True: data, addr = sock.recvfrom(MAX_MESS_LEN) thread.start_new_thread(message_handler, (data, addr,)) I would like to introduce functionality that allows me to perhaps hit 'q' to break out of the loop and end the program. I'm not sure how to do this since the program waits on the recvfrom() call until receiving a message. Is there a way to implement an interrupt key or keyboard event catcher or something?

问题 I am trying to develop a UDP application that receives data and converts the bytes into different data types. I have the code below that works when using Dart on its own. import 'dart:io'; import 'dart:typed_data'; import 'dart:mirror'; RawDatagramSocket.bind(InternetAddress.ANY_IP_V4, 20777).then((RawDatagramSocket socket){ socket.listen((RawSocketEvent e){ Datagram d = socket.receive(); if (d == null) return; ByteBuffer buffer = d.data.buffer; DKByteData data = new DKByteData(buffer); exit

问题 I am trying to develop a UDP application that receives data and converts the bytes into different data types. I have the code below that works when using Dart on its own. import 'dart:io'; import 'dart:typed_data'; import 'dart:mirror'; RawDatagramSocket.bind(InternetAddress.ANY_IP_V4, 20777).then((RawDatagramSocket socket){ socket.listen((RawSocketEvent e){ Datagram d = socket.receive(); if (d == null) return; ByteBuffer buffer = d.data.buffer; DKByteData data = new DKByteData(buffer); exit